Investments and Derivative Instruments Level 4 Offsetting Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Offsetting of Derivative Assets and Liabilities [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 852	$ 959
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	692	801
Derivative, Collateral, Obligation to Return Cash	(90)	(181)	[1]
Derivative Asset, Fair Value of Collateral	99	83	[2]
Derivative Asset, Fair Value, Amount Offset Against Collateral	61	75
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Fair Value, Gross Liability	1,255	1,345
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	499	574
Derivative, Collateral, Right to Reclaim Cash	103	49
Derivative Liability, Fair Value of Collateral	753	900	[2]
Derivative Liability, Fair Value, Amount Offset Against Collateral	(3)	(129)
Derivative Financial Instruments, Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Fair Value, Amount Offset Against Collateral	(271)	(399)
Other Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member]
Offsetting of Derivative Assets and Liabilities [Abstract]
Derivative Assets (Liabilities), at Fair Value, Net	653	722	[3]
Other Investments [Member] | Derivative Financial Instruments, Assets [Member]
Offsetting of Derivative Assets and Liabilities [Abstract]
Derivative Assets (Liabilities), at Fair Value, Net	$ (250)	$ (339)	[4]

[1] Included in other assets in the Company's Consolidated Balance Sheets and is limited to the net derivative receivable associated with each counterparty.

[2] Excludes collateral associated with exchange-traded derivatives instruments.

[3] Included in other liabilities in the Company's Consolidated Balance Sheets and is limited to the net derivative payable associated with each counterparty

[4] Included in other investments in the Company's Consolidated Balance Sheets.